Fragmented QRS (fQRS)

Fragmented QRS (fQRS)

✅ Definition

  • Fragmented QRS = Presence of additional R’ wave, notching of the R or S wave, or fragmentation in QRS complex in two contiguous leads without bundle branch block.
  • QRS duration is <120 ms (if >120 ms, the fragmentation criteria are different).

✅ Mechanism

  • fQRS represents delayed ventricular conduction due to myocardial scar, fibrosis, or ischemia.
  • Electrical impulse travels through heterogeneous tissue → multiple deflections within the QRS.

✅ ECG Criteria

  • QRS <120 ms with:
    • Additional R’ wave
    • Notching in the R or S wave
    • More than one R’ (fragmented appearance)
  • Seen in ≥2 contiguous leads corresponding to a myocardial territory.

✅ Causes / Associations

  • Coronary artery disease (CAD) / Myocardial infarction (MI)
  • Cardiomyopathy (dilated, hypertrophic, restrictive)
  • Arrhythmogenic right ventricular cardiomyopathy (ARVC)
  • Congenital heart disease
  • Sarcoidosis, myocarditis, fibrosis

✅ Clinical Significance

  • Marker of myocardial scar/fibrosis.
  • Predicts:
    • Prior MI (even when Q waves absent)
    • Arrhythmic risk (ventricular tachyarrhythmias, sudden cardiac death)
    • Poor prognosis in CAD, cardiomyopathy, and heart failure.
  • Useful in risk stratification along with LVEF.

✅ Practical Example

  • A patient with history of MI but no Q waves on ECG → fQRS may still indicate scar tissue.
  • In non-ischemic cardiomyopathy, fQRS suggests diffuse fibrosis and higher arrhythmia risk.

🔹 Key Points Summary (Quick Table)

AspectDetails
DefinitionQRS with notching, additional R’, or fragmentation in ≥2 contiguous leads
QRS DurationUsually <120 ms
MechanismDelayed conduction through scarred/fibrotic myocardium
CausesMI, CAD, cardiomyopathy, ARVC, myocarditis, sarcoidosis
PrognosisIndicates scar, predicts arrhythmias, worse outcomes in HF
Clinical UseScar detection, risk stratification for ICD/arrhythmia